Group Rankings

Create an object of class "grouped_rankings" which associates a group index with an object of class "rankings". This allows the rankings to be linked to covariates with group-specific values as the basis for model-based recursive partitioning, see pltree.

Usage

group(x, index, ...)

as.grouped_rankings(x, ...)

# S3 method for paircomp
as.grouped_rankings(x, ...)

# S3 method for grouped_rankings
[(x, i, j, ..., drop = TRUE, as.grouped_rankings = TRUE)

# S3 method for grouped_rankings
format(x, max = 2L, width = 20L, ...)

Arguments

x

a "rankings" object for group(); an object that can be coerced to a "grouped_rankings" object for as.grouped_rankings(), otherwise a "grouped_rankings" object.

index

a numeric vector of length equal to the number of rankings specifying the subject for each ranking.

...

additional arguments passed on to as.rankings by grouped_rankings or as.grouped_rankings; unused by format.

i

indices specifying groups to extract, may be any data type accepted by [.

j

indices specifying items to extract, as for [.

drop

if TRUE return single row/column matrices as a vector.

as.grouped_rankings

if TRUE return a grouped_rankings object, otherwise return a matrix/vector.

max

the maximum number of rankings to format per subject.

width

the maximum width in number of characters to format each ranking.

Value

An object of class "grouped_rankings", which is a vector of of group IDs with the following attributes:

rankings

The "rankings" object.

index

An index match each ranking to each group ID.

R

A matrix with items ordered from last to first place, for each ranking.

S

The rankings matrix with the ranks replaced by the size of the chosen set for free choices and zero for forced choices.

id

A list with elements of the adjacency matrix that are incremented by each ranking.

See also

pltree

Examples

# ungrouped rankings (5 rankings, 4 items)
R <- as.rankings(matrix(c(1, 2, 0, 0,
                          0, 2, 1, 0,
                          0, 0, 1, 2,
                          2, 1, 0, 0,
                          0, 1, 2, 3), ncol = 4, byrow = TRUE))
length(R)
#> [1] 5
R
#> [1] "1 > 2"     "3 > 2"     "3 > 4"     "2 > 1"     "2 > 3 > 4"

# group rankings (first three in group 1, next two in group 2)
G <- group(R, c(1, 1, 1, 2, 2))
length(G)
#> [1] 2

## by default up to 2 rankings are shown per group, "..." indicates if
## there are further rankings
G
#>                   1                   2 
#> "1 > 2, 3 > 2, ..."  "2 > 1, 2 > 3 > 4" 
print(G, max = 1)
#>            1            2 
#> "1 > 2, ..." "2 > 1, ..." 

## select rankings from group 1
G[1,]
#>                   1 
#> "1 > 2, 3 > 2, ..." 

## exclude item 3 from ranking
G[, -3]
#> Recoded rankings that are not in dense form
#> Rankings with only 1 item set to `NA`
#>                1                2 
#> "1 > 2, NA, ..."   "2 > 1, 2 > 4" 

## rankings from group 2, excluding item 3
## - note group 2 becomes the first group
G[2, -3]
#> Recoded rankings that are not in dense form
#>              1 
#> "2 > 1, 2 > 4" 

## index underlying rankings without creating new grouped_rankings object
G[2, -3, as.grouped_rankings = FALSE]
#>      1 2 4
#> [1,] 2 1 0
#> [2,] 0 1 3